Musculoaponeurotic architecture of the human masseter muscle: an in vivo ultrasonographic study of architectural changes during mandibular protrusion and lateral excursions.

OBJECTIVE: The present study evaluated the in vivo musculoaponeurotic architecture of the superficial head (SH) of the masseter muscle (MM) of asymptomatic participants in excursive mandibular movements compared to the relaxed state as examined with ultrasonography. It was hypothesized that the mean fiber bundle length (FBL) and mean height of the aponeurosis (HA) of the laminae of the SH would differ significantly between the relaxed state and protrusion, ipsilateral excursion, and contralateral excursion. STUDY DESIGN: The MM was studied volumetrically in 12 female and 12 male asymptomatic participants bilaterally by using ultrasound imaging. Mean FBL and HA in protrusion and ipsilateral and contralateral excursion were compared to these values in the relaxed state using paired t tests (P < .05). The intraclass correlation coefficient was used to assess intraexaminer reliability. RESULTS: The SH exhibited multiple laminae. Fiber bundles were found to attach to bone and the superior and inferior aponeuroses. Mean FBL was significantly shorter and mean HA significantly longer in protrusion and the excursions than in the relaxed state although the pattern of altered laminae and aponeuroses differed among the mandibular movements. Intraexaminer reliability was excellent. CONCLUSION: Specific changes in mean FBL and mean HA suggest differential contraction of the SH of the MM based on laminar morphology. These findings provide a baseline to investigate musculoaponeurotic changes in patients with myogenic masseter muscle pain.

Optimizing effective dose and image quality in cone beam CT sialography.

OBJECTIVES: The purpose of this study was to develop protocols that optimize patient radiation dose and image quality for cone beam computed tomographic (CBCT) sialography for the major salivary glands. STUDY DESIGN: Radiation absorbed dose measurements were repeated in triplicate using 25 sites in the head and neck of a Radiation ANalog DOsimetry system (RANDO) phantom, and effective doses were calculated across a range of peak kilovoltage (kVp) and milliamperage (mA) settings using an 8 cm (diameter) by 5 cm (height) field of view (FOV) for submandibular imaging and an 8 cm (diameter) by 8 cm (height) FOV for parotid imaging. Image signal difference-to-noise ratio (SDNR) was determined, and the figure-of-merit (FOM), a measure of image quality, was calculated. RESULTS: For submandibular sialography, 85 kVp and 6 mA were chosen as the optimal exposure parameters, resulting in a mean effective dose of 82.47 µSv and a mean SDNR of 13.86, with a mean FOM of 2.33 µSv-1. For parotid sialography, 70 kVp and 6 mA were chosen, and these settings resulted in a mean effective dose of 39.99 µSv, a mean SDNR of 17.43, and a mean FOM of 7.60 µSv-1. CONCLUSIONS: Low-dose 3-dimensional sialography with high image quality and minimal effective dose can be delivered using CBCT with localized, small FOVs.

Interexaminer Agreement in the Radiologic Identification of Apical Periodontitis/Rarefying Osteitis in the National Dental Practice-Based Research Network PREDICT Endodontic Study.

INTRODUCTION: Periapical images are routinely made in endodontics to support diagnosis and treatment decisions, but conventional imaging may not readily demonstrate inflammatory changes. This study aims to quantify disagreement in the radiologic interpretation of apical periodontitis/rarefying osteitis between 2 expert examiners and to determine if differences exist based on anatomic location. METHODS: We used 1717 pretreatment periapical images made before orthograde endodontic treatment as part of the Predicting Outcomes of Root Canal Treatment (PREDICT) study conducted within the National Dental Practice-Based Research Network. Periapical changes were assessed independently by 2 board-certified specialists, an oral and maxillofacial radiologist and an endodontist, blinded to other clinical information. If the examiners disagreed about whether a diagnosis of apical periodontitis/rarefying osteitis was justified, an adjudication was made by a third examiner. RESULTS: The overall prevalence of this radiologic diagnosis in the periapical images was 55%, and interexaminer agreement measured with the Cohen kappa statistic was calculated to be 0.56 (95% confidence interval, 0.52-0.60). Diagnostic disagreements between the 2 examiners occurred for 377 teeth (22%), with disagreements more frequent for jaw location (P = .038) and tooth type (P = .021). Differences between root number (P = .058) and jaw location and tooth groups (P = .069) were found not to be statistically significant. CONCLUSIONS: The variability of diagnostic disagreements across anatomic location and tooth type may reflect the inability of periapical images to reveal bone changes masked by the complexity and density of overlying anatomic structures, a limitation that could potentially be overcome with the use of 3-dimensional imaging.

A dynamic ultrasonographic in vivo study of the musculoaponeurotic architecture of the human masseter muscle.

OBJECTIVE: In the present study, we sought to investigate the in vivo musculoaponeurotic architecture of the masseter muscle (MM) volumetrically with ultrasound in asymptomatic participants. It was hypothesized that the mean fiber bundle length (FBL) and mean aponeurotic height of laminae of the MM differ significantly between the relaxed state and maximally contracted state upon elevation of the mandible. STUDY DESIGN: The MM was investigated volumetrically in 12 male and 12 female asymptomatic participants (mean age, 25.8 ± 4.1 years) using ultrasound. The mean FBL and mean height of aponeuroses in the relaxed and maximally contracted states were compared using paired t tests, with significance established at P ≤ .05. Intrarater reliability was assessed using the intraclass correlation coefficient (ICC). RESULTS: The MM consisted of the superficial head (SH) and deep head, each arranged in multiple laminae. Fiber bundles extended between superior and inferior aponeuroses and/or bone. Statistically significant differences (P ≤ .05) were observed in mean FBL and in mean height of aponeuroses between the relaxed and contracted states only in superficial laminae of the SH. CONCLUSIONS: These results suggest there is differential contraction of the laminae of the MM in the transition from relaxed to contracted states. Future comparison with pathologic patients can be made on the basis of an established normative database.

Radiograph prescription practices of dentists in Ontario, Canada.

BACKGROUND: With the advent of new ionizing radiation technologies, consideration must be given to the use of radiography in clinical practice. The authors aimed to determine how general dentists obtain oral and maxillofacial images and whether dentists' demographic characteristics and practice environments affect imaging decisions. METHODS: The authors conducted a cross-sectional study using an electronic survey to collect information from general dentists in Ontario, Canada's most populous province. RESULTS: The authors received 1,332 responses from 9,052 general dentists registered to practice in Ontario. A total of 57.2% of dentists used a nonindividualized approach to obtaining images for new adult dentate patients. Using clinical case scenarios, the authors found that 18.8% through 55.1% of dentists did not follow evidence-based guidelines when obtaining images. Overprescribing imaging was 5.8 times more common than underprescribing. Seeing patients after images were obtained (odds ratio [OR], 5.5), owning a panoramic and a cone-beam computed tomography imaging system (OR, 4.4), and the belief that images should be obtained to screen for occult pathoses (OR, 3.5) were the factors most strongly associated with overprescription. CONCLUSIONS: Radiography prescription practices varied considerably among general dentists in Ontario and did not conform to established guidelines. Factors other than patient needs appeared to influence imaging practices. PRACTICAL IMPLICATIONS: Overprescription of imaging by general dentists can result in unnecessary radiation exposure and financial costs to patients. To mitigate this, changes are needed in dental education, continuing education courses, and regulatory requirements.

Effectiveness of Commercial Software-Enhanced Image Artifact Reduction Software.

INTRODUCTION: Artifact reduction (AR) software has been incorporated into some cone-beam computed tomographic (CBCT) systems to reduce the severity of beam hardening (BH) artifacts and improve image quality. This study quantifies BH artifact and evaluates the effectiveness of AR in 2 CBCT systems. METHODS: Palatal roots of Dent-Alike (Dentsply Sirona, Tulsa, OK) teeth were prepared and root filled with gutta-percha and EndoSequence BC Sealer (Brasseler, Savannah, GA). Six teeth were imaged with and without AR software using the ProMax3D (Planmeca Oy, Helsinki, Finland) and the Pax-i3D (Vatech, Hwaseong-si, South Korea) systems. FSL (FMRIB, Oxford, UK) software was used to quantify the light and dark components of the BH artifact along the tooth root using a specific region of interest approach and an image-wide analysis approach. Statistical analysis was performed using paired t tests and corrected for multiple comparisons with cluster mass correction using a nonparametric statistical analysis to evaluate the differences in the artifact volumes and areas with and without AR. RESULTS: A significant reduction in the light artifact was observed with the Planmeca system (P < .05), but no significant differences were observed for either the light or dark artifacts with the Vatech system when AR was applied. There were also significant reductions in the volumes of light and dark artifacts along the entire root length when the AR was applied with the Planmeca system (cluster mass P < .05), but no significant differences were observed with the Vatech system. CONCLUSIONS: Proprietary AR software is not equally effective in reducing the light and/or dark components of CBCT BH artifacts.

The use of radiographic imaging technologies by general dentists in Ontario, Canada.

OBJECTIVE: The aim of this study was to determine the prevalence of 2-dimensional and 3-dimensional digital imaging technologies, the methods used by general dentists to limit patient exposure to ionizing radiation, and the impact of dentists' education on imaging technologies and patient dose-reducing techniques. STUDY DESIGN: A cross-sectional, web-based survey of all general dentists in Ontario was conducted. RESULTS: Responses from 1332 (14.7%) of the 9052 registered general dentists in Ontario were included in the analysis. Approximately 89% reported using digital intraoral technology, 81.1% reported owning panoramic imaging systems, 71.2% reported making referrals for cone beam computed tomography (CBCT), and 9.5% reported including CBCT in their practices. CBCT was most commonly used for dental implant treatment planning (85.8%), followed by endodontics (45.4%), evaluation of pathology (39.6%), and surgical assessment for impacted teeth or difficult extractions (36.8%). Approximately 32.7% used only collimators with a long focal point-receptor distance and 8% used only rectangular collimation; 86.9% reported using a thyroid collar when imaging patients. Differences in educational backgrounds correlated with differences in the use of imaging and dose-reducing techniques. CONCLUSIONS: There is widespread adoption of digital imaging technologies by general dentists in Ontario, including CBCT. Greater implementation of long and/or rectangular collimation could markedly reduce the ionizing radiation dose to patients. Changes in dental education curricula and continuing education course offerings may address these issues.

Structural abnormalities in the temporalis musculo-aponeurotic complex in chronic muscular temporomandibular disorders.

Some forms of chronic pain are thought to be driven and maintained by nociceptive input, which can drive plasticity within nociceptive pathways. We have previously identified abnormalities along the entire nociceptive pathway in chronic myalgic temporomandibular disorders (mTMD), including the trigeminal nerves, brainstem pathways, and in the thalamus and somatosensory cortex. These data suggest that there is a peripheral nociceptive drive in mTMD, but the source of this nociceptive activity remains unknown. Here, our aim was to determine whether structural abnormalities exist in the muscles of mastication of patients with chronic mTMD. Specifically, we tested whether the volume of the temporalis muscle and its tendon-aponeurosis complex (TAC, a structure that dissipates forces in a muscle) in mTMD patients differ compared to age- and sex-matched controls. To do so, we segmented these structures on T1-weighted structural magnetic resonance images. We found that muscle volumes in mTMD were not different to controls. However, the mTMD group had significantly smaller volumes of the bilateral temporalis TAC, and thus a smaller TAC-to-muscle volume ratio. These findings were consistent across 2 independent cohorts of 17 mTMD patients, compared to 17 age- and sex-matched controls. We propose a model where reduced TAC-to-muscle ratio could result in a predisposition to muscle tissue injury. In sum, abnormalities of the temporalis muscles in mTMD supports our hypothesis that chronic mTMD pathophysiology may be related to peripheral nociceptive barrage originating from the muscles of mastication.

A Novel Method for Characterizing Beam Hardening Artifacts in Cone-beam Computed Tomographic Images.

INTRODUCTION: The beam hardening (BH) artifact produced by root filling materials in cone-beam computed tomographic (CBCT) images is influenced by their radiologic K absorption edge values. The purpose of this study was to describe a novel technique to characterize BH artifacts in CBCT images produced by 3 root canal filling materials and to evaluate the effects of a zirconium (Zr)-based root filling material with a lower K edge (17.99 keV) on the production of BH artifacts. METHODS: The palatal root canals of 3 phantom model teeth were prepared and root filled with gutta-percha (GP), a Zr root filling material, and calcium hydroxide paste. Each phantom tooth was individually imaged using the CS 9000 CBCT unit (Carestream, Atlanta, GA). The "light" and "dark" components of the BH artifacts were quantified separately using ImageJ software (National Institutes of Health, Bethesda, MD) in 3 regions of the root. Mixed-design analysis of variance was used to evaluate differences in the artifact area for the light and dark elements of the BH artifacts. RESULTS: A statistically significant difference in the area of the dark portion of the BH artifact was found between all fill materials and in all regions of the phantom tooth root (P < .05). GP generated a significantly greater dark but not light artifact area compared with Zr (P < .05). Moreover, statistically significant differences between the areas of both the light and dark artifacts were observed within all regions of the tooth root, with the greatest artifact being generated in the coronal third of the root (P < .001). CONCLUSIONS: Root canal filling materials with lower K edge material properties reduce BH artifacts along the entire length of the root canal and reduce the contribution of the dark artifact.

The Performance of a Zirconium-based Root Filling Material with Artifact Reduction Properties in the Detection of Artificially Induced Root Fractures Using Cone-beam Computed Tomographic Imaging.

INTRODUCTION: Limited field of view cone-beam computed tomographic (CBCT) imaging has been used to augment clinical testing of vertical root fractures (VRFs); however, the presence of gutta-percha (GP) in the canal space generates substantial imaging artifacts that make fracture detection difficult. The purpose of this study was to evaluate the influence of a zirconium (Zr)-based root filling material with radiologic properties that reduce beam hardening (BH) artifacts using CBCT imaging in the in vitro diagnosis of VRFs. METHODS: One hundred seventy-six single-rooted mandibular premolar teeth were obtained, and half of these teeth were filled with GP or Zr (CPoint; EndoTechnologies, LLC, Shrewsbury, MA). VRFs were induced in 44 decoronated teeth in each group using an Instron (Norwood, MA) Universal Testing Machine. Each root was then placed in a dry human mandible and imaged with the Carestream 9000 3D CBCT system (Carestream Dental, Atlanta, GA). The images were evaluated by 6 oral maxillofacial radiologists (OMRs) and residents. RESULTS: The sensitivity was greater for detecting VRFs in the Zr group than the GP group (P = .035). However, the specificity was greater for the GP group than the Zr group (P = .028). Receiver operating characteristic area under the curve values were greater for the Zr group than the GP group, but these differences were not statistically significant. The OMRs outperformed the residents in the detection of VRFs in the Zr group with respect to specificity (P = .006) and positive predictive value (P = .012). CONCLUSIONS: The reduced BH of the Zr group improved the sensitivity of the detection of artificially induced VRFs. The ability to detect VRFs in the Zr group was further enhanced by clinical experience.

Mandibular changes on panoramic imaging after head and neck radiotherapy.

OBJECTIVES: Changes to the radiographic appearance of the jaws after head and neck radiotherapy have not been thoroughly characterized. This retrospective study examines changes to the appearance of the mandible on panoramic images following intensity-modulated radiotherapy (IMRT) and relates these changes to medical co-morbidities and radiation dose. STUDY DESIGN: The medical and dental charts, and panoramic images of 126 patients who received IMRT at the Princess Margaret Hospital between January 1, 2005, and December 31, 2008, were analyzed independently by three observers. RESULTS: Of the 126 patients, 75 (60%) had post-IMRT changes, as seen on panoramic images; most, 66 (88%), consisted of widened periodontal ligament space (WPLS). The median time to WPLS was 29 months after IMRT. Female gender and radiation dose correlated with decreased time to WPLS. CONCLUSIONS: These results indicate that WPLS is a common radiographic sequela after head and neck radiotherapy, underscoring its clinical significance as a reliable marker of irradiated bone. Furthermore, this type of WPLS needs to be differentiated from odontogenic inflammatory disease and cancer recurrence to avoid unnecessary treatment that may precipitate osteoradionecrosis.

Influence of Experience and Training on Dental Students' Examination Performance Regarding Panoramic Images.

Physician training has greatly benefitted from insights gained in understanding the manner in which experts search medical images for abnormalities. The aims of this study were to compare the search patterns of 30 fourth-year dental students and 15 certified oral and maxillofacial radiologists (OMRs) over panoramic images and to determine the most robust variables for future studies involving image visualization. Eye tracking was used to capture the eye movement patterns of both subject groups when examining 20 panoramic images classified as normal or abnormal. Abnormal images were further subclassified as having an obvious, intermediate, or subtle abnormality. The images were presented in random order to each participant, and data were collected on duration of the participants' observations and total distance tracked, time to first eye fixation, and total duration and numbers of fixations on and off the area of interest (AOI). The results showed that the OMRs covered greater distances than the dental students (p<0.001) for normal images. For images of pathosis, the OMRs required less total time (p<0.001), made fewer eye fixations (p<0.01) with fewer saccades (p<0.001) than the students, and required less time before making the first fixation on the AOI (p<0.01). Furthermore, the OMRs covered less distance (p<0.001) than the dental students for obvious pathoses. For investigations of images of pathosis, time to first fixation is a robust parameter in predicting ability. For images with different levels of subtlety of pathoses, the number of fixations, total time spent, and numbers of revisits are important parameters to analyze when comparing observer groups with different levels of experience.

The effects of voxel size on cone beam computed tomography images of the temporomandibular joints.

OBJECTIVES: This clinical study assesses the effect of cone beam computed tomography (CBCT) voxel size on the ability to detect osseous changes associated with degenerative disease of the temporomandibular joint (TMJ). The effect of voxel size on perceived CBCT image quality is also evaluated. STUDY DESIGN: Twenty-two patients presenting for TMJ imaging with suspected degenerative disease were imaged with the Carestream 9000 CBCT unit, using separate right and left joint acquisitions (n = 44). Images were archived at native and downsampled voxel resolutions of 76 µm and 300 µm, respectively. Three oral and maxillofacial radiologists evaluated the images for osseous changes, as well as image quality by using a visual analog scale. RESULTS: There was no statistically significant difference between the voxel sizes in the detection of TMJ osteoarthritic changes. The mean visual analog scale response did, however, differ significantly between the two groups (P = .02). CONCLUSIONS: Despite no improvement in diagnostic efficacy with a smaller voxel size, perceived image quality is consistently higher for images with greater spatial resolution.

Dental and dental hygiene students' diagnostic accuracy in oral radiology: effect of diagnostic strategy and instructional method.

There has been much debate surrounding diagnostic strategies and the most appropriate training models for novices in oral radiology. It has been argued that an analytic approach, using a step-by-step analysis of the radiographic features of an abnormality, is ideal. Alternative research suggests that novices can successfully employ non-analytic reasoning. Many of these studies do not take instructional methodology into account. This study evaluated the effectiveness of non-analytic and analytic strategies in radiographic interpretation and explored the relationship between instructional methodology and diagnostic strategy. Second-year dental and dental hygiene students were taught four radiographic abnormalities using basic science instructions or a step-by-step algorithm. The students were tested on diagnostic accuracy and memory immediately after learning and one week later. A total of seventy-three students completed both immediate and delayed sessions and were included in the analysis. Students were randomly divided into two instructional conditions: one group provided a diagnostic hypothesis for the image and then identified specific features to support it, while the other group first identified features and then provided a diagnosis. Participants in the diagnosis-first condition (non-analytic reasoning) had higher diagnostic accuracy then those in the features-first condition (analytic reasoning), regardless of their learning condition. No main effect of learning condition or interaction with diagnostic strategy was observed. Educators should be mindful of the potential influence of analytic and non-analytic approaches on the effectiveness of the instructional method.

The importance of the initial comprehensive dental examination.

New diagnostic technology that improves patient care is becoming more common in dental practices at both the generalist and specialist levels. However, new diagnostic tests may be ordered prematurely or given more importance than warranted, resulting in misdiagnoses or delay of appropriate treatment. In this report, we describe a case in which several oral health care professionals failed to diagnose persistent facial pain correctly, in part because of failure to conduct a comprehensive dental examination and over-reliance on new technology. During 13 months of persistent mandibular pain, various diagnoses and treatments, the patient did not have a comprehensive dental examination-an examination that would have revealed periradicular periodontitis in tooth 25 causing the referred mandibular pain. This case demonstrates the importance and value of the initial comprehensive history and clinical examination, followed by conventional imaging to arrive at an accurate diagnosis and treatment plan.

Test-enhanced learning and its effect on comprehension and diagnostic accuracy.

CONTEXT: In health professions education, tests have traditionally been used to assess the skills and knowledge of learners. More recently, research in psychology and education has shown that tests can also be used to enhance student memory; a phenomenon called the 'testing effect'. Much of the research in this domain has focused on enhancing rote memory of simple facts, and not on the deeper comprehension and application of complex theoretical knowledge necessary to diagnose and manage patients. The purpose of this study was to examine the effects of testing on students' comprehension of the basic science mechanisms and diagnostic accuracy. METHODS: Undergraduate dental and dental hygiene students (n = 112) were taught the radiographic features and pathophysiology underlying four intrabony abnormalities. Participants were divided into two groups: the test-enhanced (TE) condition and the study (ST) condition. Following the learning phase, the TE condition group completed an interventional test that tested the basic science mechanisms and the ST condition group was given additional study passages without being tested. Participants in both groups then completed a diagnostic test and a memory test immediately after the learning phase and 1 week later. RESULTS: A main effect of testing condition was found. The participants in the TE condition group outperformed those in the ST condition group on immediate and delayed testing. Unlike the diagnostic test, the memory test showed no difference between the groups. CONCLUSION: The inclusion of the basic science test appears to have improved the students' understanding of the underlying disease mechanisms learned and also improved their performance on a test of diagnostic accuracy.

Integration of basic sciences and clinical sciences in oral radiology education for dental students.

Educational research suggests that cognitive processing in diagnostic radiology requires a solid foundation in the basic sciences and knowledge of the radiological changes associated with disease. Although it is generally assumed that dental students must acquire both sets of knowledge, little is known about the most effective way to teach them. Currently, the basic and clinical sciences are taught separately. This study was conducted to compare the diagnostic accuracy of students when taught basic sciences segregated or integrated with clinical features. Predoctoral dental students (n=51) were taught four confusable intrabony abnormalities using basic science descriptions integrated with the radiographic features or taught segregated from the radiographic features. The students were tested with diagnostic images, and memory tests were performed immediately after learning and one week later. On immediate and delayed testing, participants in the integrated basic science group outperformed those from the segregated group. A main effect of learning condition was found to be significant (p<0.05). The results of this study support the critical role of integrating biomedical knowledge in diagnostic radiology and shows that teaching basic sciences integrated with clinical features produces higher diagnostic accuracy in novices than teaching basic sciences segregated from clinical features.

Optimization of exposure parameters for cone beam computed tomography sialography.

OBJECTIVES: The assessment of image quality is a crucial step in the development of a new imaging protocol. Having proposed and reported on a preliminary protocol for sialography using cone beam CT (CBCT), the purpose of this study was to further optimize this protocol by maximizing the image signal difference-to-noise ratio (SDNR) and to relate these new data to previously published dosimetric data for CBCT sialography. METHODS: An imaging phantom was constructed using samples with different concentrations of iodine and a water-immersed mandible. The CB MercuRay (Hitachi Medical Systems, Tokyo, Japan) was used to image the phantom using different peak kilovoltage (kVp) and milliamperage (mA) settings. SDNR was then calculated using the raw images based on mean pixel values (MPV) measured in selected regions of interest (ROI). Finally, a figure of merit (FOM) was calculated to examine the trade-off between image SDNR and effective radiation dose. RESULTS: The SDNR demonstrated an expected increase as the kVp increased from 60 to 120. Also, images made with the higher mA setting (15) had greater SDNR. The iodine concentration also influenced the image quality such that SDNR increased with increased amounts of iodine. The calculated FOM was greatest for the technique using 80 kVp, with equivalent results for 10 mA and 15 mA. CONCLUSION: An optimized protocol for CBCT sialography using CB MercuRay entails a 6 inch field of view with 80 kVp and 10 mA.

Osseous (cemento-osseous) dysplasia of the jaws: clinical and radiographic analysis.

OBJECTIVES: To explore the demographic characteristics and clinical features among patients with osseous (cemento-osseous) dysplasia (OD/COD) of the jaws and to determine the frequency of particular radiographic characteristics. METHODS: The charts and radiographic reports of 118 patients with OD/COD, obtained from the archives of the University of Toronto discipline of oral and maxillofacial radiology, were reviewed. Demographic and clinical data, radiographic findings and final diagnoses were collected and analyzed to determine typical characteristics. RESULTS: Of the 117 patients for whom age and sex were known, the majority (97 [82.9%]) were female; these female patients had a mean age (± standard deviation) of 44.3 ± 13.4 years. Eighty-three (72.2%) of the 115 patients for whom symptoms were known were clinically asymptomatic. Ninety-three patients (78.8%) had OD/COD at single sites (i.e., periapical OD/COD), and 25 (21.2%) had OD/COD at multiple sites (i.e., florid OD/COD). In addition, 15 (12.7%) of the cases were associated with one or more simple bone cysts, and 13 (11.0%) were associated with osteomyelitis. In most cases, the OD/COD was unilateral, with the lesion being located in the mandible, usually associated only with the posterior teeth. The lesions exhibited well-defined, sclerotic or corticated margins (108 patients [91.5%]) and were surrounded by a radiolucent border. Minimal effects on surrounding structures were observed. As well, 85 (72.0%) of the lesions were in the mixed radiolucent-radiopaque stage, with dense, cementum-like radiopacities. CONCLUSIONS: The majority of cases of OD/COD occurred in women in the fifth decade of life, and most cases were asymptomatic. OD/COD was more likely to present as solitary lesions but also occurred in association with simple bone cysts or osteomyelitis.

The effects of slice thickness and interslice interval on reconstructed cone beam computed tomographic images.

OBJECTIVE: The objective of this study was to compare the effects of varying 2 image-processing parameters, slice thickness and interslice interval, on the appearances of reconstructed cone beam CT (CBCT) images. STUDY DESIGN: Bone height was used a metric for comparing images reconstructed with different slice thicknesses and interslice intervals. We examined 102 putative implant sites in 18 subjects who had treatment planned for dental implants and who were imaged with custom-fitted imaging stents with linear radiopaque markers. Image slice thickness and interslice interval were increased in millimetric increments from 1 to 5 mm, and bone height was used to determine if varying these parameters had a bearing on the resulting images. RESULTS: Statistically significant differences were found between bone heights when slice thickness or interslice interval were varied by greater than 1 mm (P < .005). CONCLUSIONS: Understanding the effects of slice thickness and interslice interval may be important in the portrayal of both normal anatomy and pathoses in CBCT images.